氧化钛和氧化铝陶瓷的骨诱导作用

蛋白质吸附、钙磷离子释放和表面生物矿化是钙磷材料诱导异位骨生成的可能材料机制。对比了非表面微孔羟基磷灰石陶瓷(HA-S)、表面微孔羟基磷灰石陶瓷(HA-R)和表面微孔生物惰性非钙磷陶瓷(TiO_2陶瓷;Al_2O_3陶瓷;两者无钙磷释放,无表面生物矿化能力)的异位骨诱导能力。研究发现,不同化学成分的陶瓷材料对蛋白质有选择性吸附。即使不吸附骨形态发生蛋白-2(rhBMP-2),具有表面微孔的非钙磷陶瓷也能诱导异位骨组织生成。结果表明,钙磷离子释放和表面生物矿化在磷酸钙生物材料骨诱导中不起关键作用,表面微孔也不一定通过蛋白质吸附而在异位骨诱导中起作用。

3D-printed bioactive scaffolds from nanosilicates and PEOT/PBT for bone tissue engineering

Additive manufacturing(AM)has shown promise in designing 3D scaffold for regenerative medicine.However,many synthetic biomaterials used for AM are bioinert.Here,we report synthesis of bioactive nanocomposites from a poly(ethylene oxide terephthalate)(PEOT)/poly(butylene terephthalate)(PBT)(PEOT/PBT)copolymer and 2D nanosilicates for fabricating 3D scaffolds for bone tissue engineering.PEOT/PBT have been shown to support calcification and bone bonding ability in vivo,while 2D nanosilicates induce osteogenic differentiation of human mesenchymal stem cells(hMSCs)in absence of osteoinductive agents.The effect of nanosilicates addition to PEOT/PBT on structural,mechanical and biological properties is investigated.Specifically,the addition of nanosilicate to PEOT/PBT improves the stability of nanocomposites in physiological conditions,as nanosilicate suppressed the degradation rate of copolymer.However,no significant increase in the mechanical stiffness of scaffold due to the addition of nanosilicates is observed.The addition of nanosilicates to PEOT/PBT improves the bioactive properties of AM nanocomposites as demonstrated in vitro.hMSCs readily proliferated on the scaffolds containing nanosilicates and resulted in significant upregulation of osteo-related proteins and production of mineralized matrix.The synergistic ability of nanosilicates and PEOT/PBT can be utilized for designing bioactive scaffolds for bone tissue engineering.

Potential therapeutic benefits stemming from the thermal nature of irreversible electropora tion of solid cancers

To the Editor：Irreversible electroporation （IRE） is a CE- and FDA- approved treatment modality for pancreatic and liver tumors that is based on the site-confined destruction of tumor tissue by multiple short, high-intensity electrical pulses.

Exploiting biased reptation for continuous flow preparative DNA fractionation in a versatile microfluidic platform

A new approach is presented for preparative,continuous flow fractionation of sub-10-kbp DNA fragments,which exploits the variation in the field-dependent mobility of the DNA molecules based on their length.Orthogonally pulsed electric fields of significantly different magnitudes are applied to a microchip filled with a sieving matrix of 1.2% agarose gel.Using this method,we demonstrate a high-resolution separation of 0.5,1,2,5,and 10 kbp DNA fragments within 2 min.During the separation,DNA fragments are also purified from other ionic species.Preparative fractionation of sub-10-kbp DNA molecules plays an important role in second-generation sequencing.The presented device performs rapid high-resolution fractionation and it can be reliably manufactured with simple microfabrication procedures.

Large-scale fabrication of highly ordered sub-20 nm noble metal nanoparticles on silica substrates without metallic adhesion layers

Periodic noble metal nanoparticles offer a wide spectrum of applications including chemical and biological sensors,optical devices,and model catalysts due to their extraordinary properties.For sensing purposes and catalytic studies,substrates made of glass or fused-silica are normally required as supports,without the use of metallic adhesion layers.However,precise patterning of such uniform arrays of silica-supported noble metal nanoparticles,especially at sub-100 nm in diameter,is challenging without adhesion layers.In this paper,we report a robust method to large-scale fabricate highly ordered sub-20 nm noble metal nanoparticles,i.e.,gold and platinum,supported on silica substrates without adhesion layers,combining displacement Talbot lithography(DTL)with dry-etching techniques.Periodic photoresist nanocolumns at diameters of~110 nm are patterned on metal-coated oxidized silicon wafers using DTL,and subsequently transferred at a 1:1 ratio into anti-reflection layer coating(BARC)nanocolumns with the formation of nano-sharp tips,using nitrogen plasma etching.These BARC nanocolumns are then used as a mask for etching the deposited metal layer using inclined argon ion-beam etching.We find that increasing the etching time results in coneshaped silica features with metal nanoparticles on the tips at diameters ranging from 100 nm to sub-30 nm,over large areas of 3×3 cm^(2).Moreover,subsequent annealing these sub-30 nm metal nanoparticle arrays at high-temperature results in sub-20 nm metal nanoparticle arrays with~10^(10) uniform particles.

Spermine induced reversible collapse of deoxyribonucleic acid-bridged nanoparticle-based assemblies

DNA-linked 2D and 3D nano-assemblies find use in a diverse set of applications, ranging from DNA-origami in drug delivery and medical imaging, to DNA-linked nanoparticle structures for use in plasmonics and （bio）sensing. However, once these structures have been fully assembled, few options are available to modulate structure geometry. Here, we investigated the use of the polycation spermine to induce DNA collapse in small oligonucleotide-linked （54 bp） gold nanoparticle structures by monitoring shifts in the localized surface plasmon resonance （LSPR） peak and by comparing the data with finite-difference time-domain （FDTD） simulations. Our data shows that low concentrations of spermine can be applied to induce large changes in DNA conformation, leading to a significant reduction in interparticle distance （from - 25 to - 3 nm） and enhanced plasmonic coupling. The DNA collapse is near-instantaneous and reversible, and its application at low and high DNA densities is demonstrated with surface plasmon resonance imaging （SPRi）, showing the potential of spermine to dynamically modulate distances and geometry in DNA-based nano-assemblies.